EP 0 651 147 B1 discloses an arrangement in which the legs at the opposite ends of the spring jointly engage the rotor part and the housing part and if electrical drive of the rotor is shut off or fails, the throttle valve will be brought to a neutral or rest position corresponding to a start position or idle emergency position.
In this neutral position, the spring is relaxed and free of stress and it has been found that objectionable fluctuations of speed of the internal combustion engine occur.